To avoid waste of research, no new studies should be done without a systematic review of existing evidence, argue Hans Lund and colleagues

Whether or not today’s medical researchers, like Isaac Newton, see themselves as “standing on the shoulders of giants,” they might still be expected to build systematically on previous research when planning new studies. Even though this issue was highlighted as early as 2005,12 numerous studies indicate that researchers do not use a systematic methodology to identify and refer to earlier research when justifying, designing, or discussing new research.34567891011 This is true, even in high quality clinical studies published in the most prestigious medical journals.45812 Rather, medical researchers select studies to cite based primarily on preferences and strategic considerations.131415161718 The term “evidence based research” was coined in 2009 to indicate the approach that is needed to reduce this practice, which is an important source of research waste19 and risks unnecessary harm for patients and study participants.

In view of the easy access to both electronic research databases and high quality systematic reviews—spearheaded by groups such as the Cochrane Collaboration, and numerous evidence synthesis centres worldwide—there is little excuse for researchers failing to refer to current systematic assessments of previous research. Nevertheless, authors seem to get away with being very selective,1314 preferentially citing studies with results that support the intervention they are evaluating.15161718 Some research funders have already taken action. For example, the National Institute for Health Research in England now requires that applicants for primary research funding justify any proposed research by referencing a current systematic review of relevant existing research to show that they have taken account of the …